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Old 2016-05-11, 23:57   #111
Prime95
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Default Nearly all done!

Photos as promised. 2 shots from the side and 1 from the front. Finally for the first time ever, 1 with the side panels on.
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Old 2016-05-12, 00:00   #112
Prime95
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Temps for 6 CPUs are good -- upper 50s to mid 60s.

The 7th CPU at the bottom in the back is mid 70s -- could be a problem.
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Old 2016-05-12, 01:04   #113
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Quote:
Originally Posted by Prime95 View Post
Temps for 6 CPUs are good -- upper 50s to mid 60s.

The 7th CPU at the bottom in the back is mid 70s -- could be a problem.
Zip-tying a case fan to the PCI slots would probably solve that.
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Old 2016-05-12, 01:29   #114
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Physics question: With the case closed, temps go up. Could this necessitate a voltage increase?

I ask, because the previously stable CPU in the lower rear crashes with temps now in the mid-70s.
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Old 2016-05-12, 04:12   #115
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Quote:
Originally Posted by Prime95 View Post
Physics question: With the case closed, temps go up. Could this necessitate a voltage increase?

I ask, because the previously stable CPU in the lower rear crashes with temps now in the mid-70s.
Temperature can affect electron leakage. You might have to bump the voltage or improve the cooling.

I would try a case fan first, since having cooler air in the case should reduce the fan speeds of the CPU fans and maybe even save energy instead of increasing it by bumping the voltage. I'd run the fan off a case fan header on the hot board.
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Old 2016-05-12, 10:16   #116
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Quote:
Originally Posted by Prime95 View Post
With the case closed, temps go up.
I found formulas like this very helpful

Quote:
Cooling = 0.317 * ΔT * CFM

Where:

Cooling is in Watts
ΔT is the difference in air temperature (°F) between the intake and exhaust
CFM is the airflow through the chassis in cubic feet per minute
So for 300 W of heat and ΔT of 20 F, a case needs
300 / 20 / 0.317 = 47 CFM

If the outside air is 70 F then parts of the case air will be at 90 F.
Many quite fans are in the 10 to 20 CFM range.
My 100 CFM fans draw 0.8 Amp so a 0.1 A fan is about 12 CFM.
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Old 2016-05-14, 19:18   #117
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Quote:
Originally Posted by bgbeuning View Post
If the outside air is 70 F then parts of the case air will be at 90 F.
Many quite fans are in the 10 to 20 CFM range.
My 100 CFM fans draw 0.8 Amp so a 0.1 A fan is about 12 CFM.
I wonder if George should even go old school and get a 120v case fan (local electronics store should have them, but definitely online too).

Super high CFM... If it were me I'd probably have it blowing *in* so it creates more airflow inside the case (and probably turbulent enough that the air will move past every nook and cranny).

One thing I've picked up on with server designs is that they use plastic baffles to channel the air over the parts that need it. It's not enough just to slap a few fans at the intake and assume air will go where it needs to go... they channel that air specifically over the CPU, memory, and other high temp things (array controller).

So George might also consider if maybe the air is exchanging at a high enough rate, but it's obviously not getting to that one board as well as the others just due to it's position. Maybe use some cardboard to try and funnel air into better places? It would probably take some experimentation...

But clearly that's what's happening once the case is buttoned up. If it works okay when the covers are off, air is getting into places that it can't when the walls are up.
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Old 2016-05-18, 07:30   #118
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Quote:
Originally Posted by Madpoo View Post
If it were me I'd probably have it blowing *in* so it creates more airflow inside the case (and probably turbulent enough that the air will move past every nook and cranny).
Just need to make sure that the fan at the back can handle the inflow (i.e. make sure the push-pull fan setup is balanced right)

Quote:
One thing I've picked up on with server designs is that they use plastic baffles to channel the air over the parts that need it. It's not enough just to slap a few fans at the intake and assume air will go where it needs to go... they channel that air specifically over the CPU, memory, and other high temp things (array controller).
Another thing that can happen in server rooms is have hot and cold air channels.
Completely separated so that you are only allowed to draw air from the cold channel, and only allowed to discharge the exhaust into the warm channel.
For a desk setup I guess you could use air conditioning ducting to supply the pull fans, and have some kind of heat exchanger to pump the cold air down it.

Last fiddled with by 0PolarBearsHere on 2016-05-18 at 07:30
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Old 2016-05-18, 15:48   #119
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Quote:
Another thing that can happen in server rooms is have hot and cold air channels.
Attach a plastic dryer duct to your case exhaust and vent it outside. There are expandable plates with duct connection that fit in a (sash) window.
You might even be able to reverse this setup and bring cold air to your intakes in winter.

Last fiddled with by kladner on 2016-05-18 at 15:49
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Old 2016-05-18, 16:39   #120
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Quote:
Originally Posted by kladner View Post
Attach a plastic dryer duct to your case exhaust and vent it outside. There are expandable plates with duct connection that fit in a (sash) window.
You might even be able to reverse this setup and bring cold air to your intakes in winter.
I've thought about doing that before, but the problem with the plastic dryer duct is that the inside is rippled, which creates a lot of back-pressure that a case fan has trouble overcoming. That's not even taking into account wind or pressure changes when running a dryer or a bathroom fan. So you end up having to run a big noisy fan.

Piping cold air in can be bad when the air is moist for obvious reasons. I've thought about running an outdoor cluster but I've yet to find a good solution for dealing with humidity/rain/snow.

About the most efficient thing to do on the home scale is to pipe the exhaust into the air return of the central air system. When it's heating, it will distribute that heat, and when it's cooling, it will cool the hottest air, which is more efficient.

You could turn your basement into a server room if you have one. Personally I'd set up a thermal syphon using a black pipe outside: the sunshine would heat the air in the pipe causing it to rise and pull air in from the bottom which could be connected to the exhaust from the computers. Any wind blowing by the exit of the pipe would tend to suck air out from the Bernoulli Effect. Cupolas on old houses were originally built to do essentially that.
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Old 2016-05-19, 01:15   #121
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Quote:
Originally Posted by Mark Rose View Post
About the most efficient thing to do on the home scale is to pipe the exhaust into the air return of the central air system. When it's heating, it will distribute that heat, and when it's cooling, it will cool the hottest air, which is more efficient.
I assume it takes just as much AC power to cool air as it does to heat it.
So if a PC is putting out 500 W of heat, the HVAC uses 500 W of AC power
to remove the heat. So if my electric bill went up X from running a PC then
it will go up 2X if the PC is in an area cooled by HVAC.

After thinking about it, I am not sure why I think this. Is it true?
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